fuck about

fuck around

verb (adverb) offensive, taboo, slang

(intr) to act in a stupid or aimless manner
(tr) to treat (someone) in an inconsiderate or selfish way

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012